Urinary incontinence is extremely widespread in the developed countries. Thomas, Plymat, Blannin and Meade, writing in the British Medical Journal in November 1980, stated that in their large scale survey, 8.5% of women and 1.6% of men in the age group 15-64 are regularly incontinent and that in the 65 and over age group the incidence rises to 11.6% in women and 6.9% in men. This study in London and South Wales suggests that in the United Kingdom there may be nearly 2.5 million regularly incontinent of urine and nearly twice as many who are occasionally incontinent. There seems to be no grounds for believing that the incidence is significantly less in other major European countries and the United States.
It is now well understood that urinary incontinence in women is due to two main causes which may occur alone or together. Genuine Stress Incontinence (GSI) is the accepted International Continence Society term for incontinence caused by incompetence or weakness of the bladder neck and proximal urethra in response to stress events such as coughing, laughing or vigorous postural change. The second cause, Detrusor Instability (DI) involves unstable and involuntary contractions of the bladder; these may also be initiated by a stress event and commonly give rise to symptoms of urge, frequency, and nocturia. Since the causes for the two types of incontinence are different, the treatments are not the same. For example, for GSI, treatment may be by physiotherapy if the condition is mild, but more usually there is recourse to surgery. For DI, surgery has generally proved unsuccessful.
DI is detected by cystometry. In practice, cystometry is generally carried out using equipment which measures the pressure response of the bladder to filling at a constant monitored rate.
Conventional cystometric equipment has generally been expensive and sophisticated. In addition to recording pressure inside the bladder, it also records the intra-abdominal pressure (that pressure within the abdomen due to the presence and movement of the viscera). The pressure due to detrusor contraction is measured by the use of a catheter in the bladder, that due to intra-abdominal pressure by a balloon on a catheter in the rectum. Both of these pressures are typically displayed on pen recorder charts and an additional channel electronically subtracts the visceral pressure from the apparent bladder pressure to reveal the component which is solely due to contractions of the detrusor muscle.
Simpler alternatives are possible. In 1982, Bajpai, Sutherst and Brown reported to the 12th Annual Meeting of the International Continence Society their results comparing a simple single-channel cystometer with sophisticated multi-channel equipment on a single-blind crossover basis. They found agreement in findings between the two methods in more than 90% of cases and there were no false negatives. This latter point is important since a negative result on cystometry in the presence of incontinent symptoms would suggest a diagnosis of GSI and, as indicated, that could lead to an erroneous decision to undertake surgery.
With regard to the treatment of DI, probably the most encouraging work has been carried by Willington and Cardozo et al in the United Kingdom. That work involved mild therapeutic distension of the bladder in what has been referred to as the "biofeedback principle." Unlike other more complicated methods of treatment, the Willington et al treatment is simple, innocuous, effective, repeatable, and lacks adverse side effects.
Willington employed an apparatus sold commercially under the name "Cystomat" disclosed by Holm and Egleblad in The Journal of Urology in 1970. The authors describe a siphon device for tidal drainage of the bladder although they do not appear to have contemplated use of the device either as a cystometer or for biofeedback treatment of DI. The Cystomat does, however, feature a tubing arrangement which makes such applications possible.
Published British application No. 2 151 139A (D. E. Young) discloses a cystometric apparatus in which three rigid tubes are clipped together to provide a device for use in a system for diagnosing and treating urinary incontinence caused by detrusor instability. Two of the rigid tubes are formed of opaque material; the third is transparent and functions as an observation tube. The upper ends of the tubes are connected by a headpiece with a vented channel between the observation tube and one of the opaque tubes. The device is attached to a source of sterile fluid and to a patient's bladder by means of flexible tubing and a catheter, and a bag or other collecting receptacle also communicates with the device. The apparatus, although notably effective in diagnosing and treating DI, requires the use of specialized rigid transparent and opaque tubing. Twisting and other stresses imposed on the tubing during handling and sterilization procedures may weaken or disrupt the connections between the tubes and the members that hold them together. Such stresses may be particularly severe because of the substantial length of the rigid tubes and their relatively small diameter. Rigidity of the tubes is important in the operation of the system, at which time the tubes must be vertically oriented, but such rigidity may present a problem of breakage which, should it occur, would disrupt the integrity and sterility of the system. The rigid tubes must also have certain of their ends coupled to flexible tubulature that communicates with a fluid source, a catheter, and a collection vessel, and such junctions between rigid and flexible tubing always present risks of possible disconnection.
Accordingly, an important aspect of this invention is to provide a device for diagnosing and treating urinary incontinence due to detrusor instability which achieves all of the advantages of prior devices without the disadvantages inherent in earlier systems. The components of this device may be easily assembled, either by a manufacturer or user, utilizing flexible, transparent tubing of the type commonly used in medical applications. The sections of tubing that function as components of the measuring device are securely held in straight, parallel condition by a rigid, opaque body component. Because of the orientation of the tubes and the configuration and opacity of the body, a user may readily observe the fluid level in the transparent observation tube while, at the same time, the parallel sections of the other transparent tubes are concealed from view.
Briefly, the cystometric device comprises a straight, vertically-elongated body formed of rigid and opaque material (or a transparent material subsequently treated to make it opaque) that may conveniently be formed by extrusion. The body is of substantially uniform cross section throughout its length and has a front face and a rear face. A vertical front channel extends along the length of the front face and a pair of rear channels extend along the length of the rear face. In a preferred embodiment, the body is essentially triangular in cross section with the front channel extending along the apex and the rear channels extending along the base of the triangle.
The plural channels may be identical in size and configuration, each being of incomplete circular shape, that is, of generally C-shaped cross sectional configuration. Each channel therefore has a longitudinal opening that communicates with the interior of the channel, with the longitudinal opening of the front channel facing in a direction opposite from the longitudinal openings of the rear channels. The width of each longitudinal opening is sufficient to permit the lateral insertion and removal of a resilient tube into and out of each of the channels and, ideally, the diameter of each channel is slightly smaller than the tube's outside diameter so that the recovery forces exerted by the tube provide a secure frictional interfit between the parts.
Other features, advantages, and objects will appear from the drawings and detailed description of preferred embodiments.